<!DOCTYPE html>
<html>
<head>
<style>
#parent {
  width: 200px;
  height: 200px;
  margin-left: 10px;
  background: green;
}
#child {
  width: 90px;
  height: 90px;
  background: red;
}
</style>
</head>
<body>
<div id="parent">
  <div id="child"></div>
</div>
</body>
</html>
